Evaluation of variability and quality control procedures for a receptor-binding assay for paralytic shellfish poisoning toxins.

The receptor-binding assay (RBA) method for determining saxatoxin (STX) and its numerous analogues, which cause paralytic shellfish poisoning (PSP) in humans, was evaluated in a single laboratory study. Each step of the assay preparation procedure including the performance of the multi-detector TopCount® instrument was evaluated for its contribution to method variability. The overall inherent RBA variability was determined to be 17%. Variability within the 12 detectors was observed; however, there was no reproducible pattern in detector performance. This observed variability among detectors could be attributed to other factors, such as pipetting errors. In an attempt to reduce the number of plates rejected due to excessive variability in the method's quality control parameters, a statistical approach was evaluated using either Grubbs' test or the Student's t-test for rejecting outliers in the measurement of triplicate wells. This approach improved the ratio of accepted versus rejected plates, saving cost and time for rerunning the assay. However, the potential reduction in accuracy and the lack of improvement in precision suggests caution when using this approach. The current study has recommended an alternate quality control procedure for accepting or rejecting plates in place of the criteria currently used in the published assay, or the alternative of outlier testing. The recommended procedure involves the development of control charts to monitor the critical parameters identified in the published method (QC sample, EC50, slope of calibration curve), with the addition of a fourth critical parameter which is the top value (100% binding) of the calibration curve.

Biocompatibility and physicochemical characteristics of alginate-polycation microcapsules.

There is a need for better understanding of the biocompatibility of alginate-polycation microcapsules based on their physicochemical characteristics. Microcapsules composed of alginate with 44% (IntG) or 71% (HiG) guluronate, gelled with calcium (Ca) or barium (Ba) and coated with poly-L-lysine (PLL) or poly-l-ornithine (PLO), followed by IntG alginate were compared. For microcapsules with an IntG(Ca) gel core, using PLO instead of PLL resulted in less immune cell adhesion after 2 days in C57BL/6J mice. The PLO microcapsules were also characterized by greater hydrophilicity and superior resistance to swelling and damage under osmotic stress. For microcapsules with a PLL membrane, replacing the IntG(Ca) gel core with IntG(Ba) or HiG(Ca) gel resulted in stronger immune responses (p<0.05). This was explained by poor penetration of PLL into the gel, as demonstrated by Fourier transform infrared spectroscopy analyses and membrane rupturing during osmotic swelling. X-ray photoelectron spectroscopy analyses show that all microcapsules had the same amount of polycation at their surface. Moreover, alginate coatings had non-significant effects on the biocompatibility and physicochemical properties of the microcapsules. Thus, alginate-polycation interactions for membrane formation are more important for biocompatibility than either the quantity of polycation at the surface or the alginate coating.

Novel symptomatology and changing epidemiology of domoic acid toxicosis in California sea lions (Zalophus californianus): an increasing risk to marine mammal health.

Harmful algal blooms are increasing worldwide, including those of Pseudo-nitzschia spp. producing domoic acid off the California coast. This neurotoxin was first shown to cause mortality of marine mammals in 1998. A decade of monitoring California sea lion (Zalophus californianus) health since then has indicated that changes in the symptomatology and epidemiology of domoic acid toxicosis in this species are associated with the increase in toxigenic blooms. Two separate clinical syndromes now exist: acute domoic acid toxicosis as has been previously documented, and a second novel neurological syndrome characterized by epilepsy described here associated with chronic consequences of previous sub-lethal exposure to the toxin. This study indicates that domoic acid causes chronic damage to California sea lions and that these health effects are increasing.

Results of a comprehensive hospital-based wound survey.

OBJECTIVE: To evaluate the prevalence, clinical aspects and management of wounds in a hospital. METHOD: A one-day survey was undertaken in our university hospital. All hospitalised patients (n=624) were examined. The clinical aspects, aetiology and management (pain, cleansing and primary dressing) of wounds were systematically evaluated. RESULTS: A total of 327 patients (52%) had 933 wounds (mean 2.8 per patient). The prevalence was higher in surgical departments (82%) than medical departments (37%), although wounds in the latter departments were larger, deeper, more painful and less numerous per patient. Pain at wound dressing changes was treated in 89% of cases; antiseptics were used for wound cleansing in 14% of cases; the primary dressing used was appropriate in fewer than 50% of cases in the medical departments. CONCLUSION: This study highlights the high prevalence of wounds in this hospital setting. Many problems with their management have been identified and measures will be taken to optimise care.

Domoic acid toxicity in Californian sea lions (Zalophus californianus): clinical signs, treatment and survival.

Eighty-one Californian sea lions (Zalophus californianus) with signs of domoic acid toxicity stranded along the coast of California in 1998 when there were blooms of the domoic acid-producing alga Pseudonitzschia australis off-shore. In 2000, a further 184 sea lions stranded with similar clinical signs, but the strandings occurred both during detectable algal blooms and after the blooms had subsided. The clinical signs in these 265 Californian sea lions included seizures, ataxia, head weaving, decreased responsiveness to stimuli and scratching behaviour. Affected animals had high haematocrits, and eosinophil counts, and high activities of serum creatine kinase. They were treated supportively by using fluid therapy, diazepam, lorazepam and phenobarbitone. Fifty-five of the 81 sea lions (68 per cent) affected in 1998 and 81 of the 184 (44 per cent) affected in 2000 died despite the treatment. Three of the 23 sea lions which survived in 1998 were tracked with satellite and radiotransmitters; they travelled as far south as San Miguel Island, California, and survived for at least three months. Eleven of the 129 animals which were released stranded within four months of being released.

Detection of norwalk-like virus in shellfish implicated in illness.

In the 1990s, Norwalk-like viruses (NLVs) were identified in patient specimens as the primary pathogen associated with shellfish-borne gastroenteritis in the United States. Identification of these viruses from implicated shellfish has been difficult due to inefficient recovery of viruses, natural polymerase chain reaction (PCR) inhibitors in shellfish, and low virus contamination. Recent improvements to the method of detecting NLVs in shellfish include enhanced processing of virus and shellfish samples, application of nested PCR and nucleotide sequencing, and increased knowledge of NLV genetic diversity. Using a newly developed and sensitive method, an NLV G2 strain was identified in 2 oyster samples implicated in a 1998 California outbreak involving 171 cases. NLV capsid primers demonstrated a greater specificity of PCR detection than did polymerase primers. The 175-base viral capsid nucleotide sequences derived from oysters were 100% identical to those derived from a patient stool sample. This finding supports the epidemiologic associations indicating that contaminated shellfish serve as the vehicle for NLV transmission.

Orthopedic management in autosomal recessive spastic ataxia of Charlevoix-Saguenay.

OBJECTIVE: To review the orthopedic management of choice in patients having autosomal recessive spastic ataxia of Charlevoix-Saguenay (ARSACS). DESIGN: A retrospective study from April 1978 to April 1997. SETTING: Centre hospitalier de la Sagamie, Chicoutimi, Que. PATIENTS: A review of the records of patients having ARSACS who were identified in the registry of the Neuromuscular Diseases Clinic at the Centre hospitalier de la Sagamie revealed 26 patients who received surgical orthopedic treatment. Initially, the patients were offered conservative treatment, which consisted of physiotherapy sessions, the wearing of an ankle-foot orthosis or serial casting. When this was unsuccessful, foot surgery was considered. RESULTS: During the study period, 49 orthopedic procedures were done, including 24 triple arthrodeses; of these, 9 were combined with lengthening of the Achilles tendon. Most triple arthrodeses were done in patients between the ages of 30 and 49 years. The surgical options evolved during the study from Lambrinudi arthrodesis through arthrodesis of the ankle to triple arthrodesis with lengthening of the Achilles tendon. CONCLUSIONS: As a complement to conservative treatment, surgery has a place in the care of patients with ARSACS. Clinically, the most effective surgical procedures are triple arthrodesis with percutaneous lengthening of the Achilles tendon and adductor and psoas tenotomies combined with neurectomy of the obturator nerve for perineal hygiene.

[Long-term results of the treatment of eventrations by intraperitoneal non-absorbable prosthesis (149 patients)]. / Résultats à long terme du traitement des éventrations par prothèse non résorbable intrapéritonéale (149 patients).

The authors report a series of 149 cases of incisional hernia, operated between 1983 and 1993, by insertion of a non-absorbable prosthetic mesh within the intraperitoneal cavity. This series consisted of 93 women and 56 men, with a mean age 57 years. One third of repairs were performed because of primary treatment failure. One or more operative risk factors were present in 127 patients. A non-absorbable intraperitoneal prosthetic mesh was inserted with tension to allow good musculo-aponeurotic repair. Postoperative mortality was 0.6%. All but 13 of the patients, were reviewed with a mean follow-up of 83 months. Twenty eight patients (20%) developed recurrence. In 8 cases, the cause of recurrence was failure of prosthetic mesh insertion because of excessive tension. Three patients (1.7%) developed a fistula in contact with the prosthetic mesh, that had to be removed. A small bowel fistula was observed in 2 cases after an intraoperative wound in 1 case, and a colonic fistula in 1 case. The results of incisional hernia repair with nonabsorbable intraperitoneal prosthetic mesh can be compared with these of other techniques using prosthetic materials. This technique does not require dissection of the intermediate planes and avoids undermining which causes substantial bleeding. The risk of sepsis is also decreased by deep placement of the prosthesis. The exceptional cases of fistula or the possibility of migration of the prosthesis are not exclusively observed with this technique, but must clearly encourage a very strict aseptic technique, with placement of omentum between the prosthetic mesh and the viscera.

[Laparoscopic treatment of common bile duct lithiasis. Study of 56 cases]. / Traitement laparoscopique de la lithiase de la voie biliaire principale. Etude de 56 cas.

AIM OF THE STUDY: The aim of this retrospective study was to report the results of the laparoscopic management of common bile duct stones in an unicentric series of 56 patients. PATIENTS AND METHOD: From January 1993 to April 1998, 56 patients, 38 women, 18 men (mean age: 59.2 years), underwent a common bile duct exploration for lithiasis through a laparoscopic approach. The patients were hospitalised for angiocholitis (n = 13), cholecystitis (n = 11), biliary pain (n = 29, nine with jaundice), pancreatitis (n = 3), abnormality of hepatic profile (n = 1). All the patients underwent an intraoperative cholangiography. Removal of the stones was tried in 50 cases through a choledochotomy, in four through the cystic duct, using Mirrizi forceps, or Dormia and Fogarty catheters in case of failure. External biliary drainage and postoperative cholangiography were done systematically. The average diameter of the common bile duct was 10.5 mm (6-20 mm). RESULTS: In 41 patients, removal of the stones was laparoscopically successful. In 11 patients, a conversion into laparotomy was necessary for several reasons. In three patients with common bile duct of small diameter, the stones were abandoned for a further endoscopic sphincterotomy. There was no mortality and the morbidity rate was 7%. The mean postoperative hospital stay was 8.6 days (4-20) for all the series and 7.8 days in case of successful laparoscopic management. CONCLUSION: In 73% of the patients, the treatment of the common bile duct lithiasis could be achieved laparoscopically, but conventional approach and endoscopic sphincterotomy are still useful in case of failure of the laparoscopic management.

Responses of the phototransduction cascade to dim light.

The biochemistry of visual excitation is kinetically explored by measuring the activity of the cGMP phosphodiesterase (PDE) at light levels that activate only a few tens of rhodopsin molecules per rod. At 23 degrees C and in the presence of ATP, the pulse of PDE activity lasts 4 s (full width at half maximum). Complementing the rod outer segments (ROS) with rhodopsin kinase (RK) and arrestin or its splice variant p44 does not significantly shorten the pulse. But when the ROS are washed, the duration of the signal doubles. Adding either arrestin or p44 back to washed ROS approximately restores the pulse width to its initial value, with p44 being 10 times more efficient than arrestin. This supports the idea that, in vivo, capping of phosphorylated R* is mostly done by p44. When myristoylated (14:0) recoverin is added to unwashed ROS, the pulse duration and amplitude increase by about 50% if the free calcium is 500 nM. This effect increases further if the calcium is raised to 1 microM. Whenever R* deactivation is changed--when RK is exogenously enriched or when ATP is omitted from the buffer--there is no impact on the rising slope of the PDE pulse but only on its amplitude and duration. We explain this effect as due to the unequal competition between transducin and RK for R*. The kinetic model issued from this idea fits the data well, and its prediction that enrichment with transducin should lengthen the PDE pulse is successfully validated.

Ageing and free radical formation. A biochemical approach to evaluate the efficacy of cosmetic preparations.

Synopsis A new method is described for studying the in vivo formation of oxygen reactive species (free radicals) in humans after exposure to UV radiation. The procedure is based on the quantitative determination in urine of (i) metabolic products of pentane, a hydrocarbon formed during lipid peroxidation, and (ii) thymine hydroxylated bases and deoxyribonucleosides as indices of DNA repair that has taken place. Creams containing UV filters protect the organism against free radical formation. Subjects using such cosmetic preparations during complete body tanning sessions do, in fact, have reduced urinary excretion of 2-pentanol and hydroxythmine derivatives.